A Supination Splint Worn Distal to the Elbow:: A Radiographic, Electromyographic, and Retrospective Report

Abstract

The purposes of this study were to 1) describe a dynamic supination splint that does not cross the humeroulnar and humeroradial joints, allowing flexion and extension of the elbow; 2) provide retrospective data on effectiveness of this splint in patients with limited supination; and 3) provide data from radiography and electromyography (EMG) that document this splint's ability to provide a passive supination force. Eleven subjects treated for various elbow and/or wrist fractures leading to losses of forearm supination significantly increased their passive range of motion (PROM) from 34.0° at the initial visit to 82.3° at discharge and active range of motion (AROM) from 27.0° to 72.3°. Radiographic images of the radius and ulna were identical in maximal voluntary supination and resting in the splint. Surface EMG was used to measure supinator muscle activity at rest, passively supinated while wearing the splint, and during a maximal isometric supination effort (without splint). Average supinator EMG activity was 7.9 mV at rest, 7.8 mV in the splint, and 68.0 mV with maximal isometric contraction. Results indicate the supination splint is clinically effective in increasing supination PROM. EMG data and radiographs indicate that the splint passively positions the forearm in supination even though the proximal margin of the splint does not cross the elbow.